Thomas H. Howard

Hydroxycarbamide in very young children with sickle-cell anaemia: a multicentre, randomised, controlled trial (BABY HUG)

BACKGROUND Sickle-cell anaemia is associated with substantial morbidity from acute complications and organ dysfunction beginning in the first year of life. Hydroxycarbamide substantially reduces episodes of pain and acute chest syndrome, admissions to hospital, and transfusions in adults with sickle-cell anaemia. We assessed the effect of hydroxycarbamide therapy on organ dysfunction and clinical complications, and examined laboratory findings and toxic effects. METHODS This randomised trial was undertaken in 13 centres in the USA between October, 2003, and September, 2009. Eligible participants had haemoglobin SS (HbSS) or haemoglobin Sβ(0)thalassaemia, were aged 9-18 months at randomisation, and were not selected for clinical severity. Participants received liquid hydroxycarbamide, 20 mg/kg per day, or placebo for 2 years. Randomisation assignments were generated by the medical coordinating centre by a pre-decided schedule. Identical appearing and tasting formulations were used for hydroxycarbamide and placebo. Patients, caregivers, and coordinating centre staff were masked to treatment allocation. Primary study endpoints were splenic function (qualitative uptake on (99)Tc spleen scan) and renal function (glomerular filtration rate by (99m)Tc-DTPA clearance). Additional assessments included blood counts, fetal haemoglobin concentration, chemistry profiles, spleen function biomarkers, urine osmolality, neurodevelopment, transcranial Doppler ultrasonography, growth, and mutagenicity. Study visits occurred every 2-4 weeks. Analysis was by intention to treat. The trial is registered with ClinicalTrials.gov, number NCT00006400. FINDINGS 96 patients received hydroxycarbamide and 97 placebo, of whom 83 patients in the hydroxycarbamide group and 84 in the placebo group completed the study. Significant differences were not seen between groups for the primary endpoints (19 of 70 patients with decreased spleen function at exit in the hydroxycarbamide group vs 28 of 74 patients in the placebo group, p=0·21; and a difference in the mean increase in DTPA glomerular filtration rate in the hydroxycarbamide group versus the placebo group of 2 mL/min per 1·73 m(2), p=0·84). Hydroxycarbamide significantly decreased pain (177 events in 62 patients vs 375 events in 75 patients in the placebo group, p=0·002) and dactylitis (24 events in 14 patients vs 123 events in 42 patients in the placebo group, p<0·0001), with some evidence for decreased acute chest syndrome, hospitalisation rates, and transfusion. Hydroxyurea increased haemoglobin and fetal haemoglobin, and decreased white blood-cell count. Toxicity was limited to mild-to-moderate neutropenia. INTERPRETATION On the basis of the safety and efficacy data from this trial, hydroxycarbamide can now be considered for all very young children with sickle-cell anaemia. FUNDING The US National Heart, Lung, and Blood Institute; and the National Institute of Child Health and Human Development.

Controlled Trial of Transfusions for Silent Cerebral Infarcts in Sickle Cell Anemia

BACKGROUND Silent cerebral infarcts are the most common neurologic injury in children with sickle cell anemia and are associated with the recurrence of an infarct (stroke or silent cerebral infarct). We tested the hypothesis that the incidence of the recurrence of an infarct would be lower among children who underwent regular blood-transfusion therapy than among those who received standard care. METHODS In this randomized, single-blind clinical trial, we randomly assigned children with sickle cell anemia to receive regular blood transfusions (transfusion group) or standard care (observation group). Participants were between 5 and 15 years of age, with no history of stroke and with one or more silent cerebral infarcts on magnetic resonance imaging and a neurologic examination showing no abnormalities corresponding to these lesions. The primary end point was the recurrence of an infarct, defined as a stroke or a new or enlarged silent cerebral infarct. RESULTS A total of 196 children (mean age, 10 years) were randomly assigned to the observation or transfusion group and were followed for a median of 3 years. In the transfusion group, 6 of 99 children (6%) had an end-point event (1 had a stroke, and 5 had new or enlarged silent cerebral infarcts). In the observation group, 14 of 97 children (14%) had an end-point event (7 had strokes, and 7 had new or enlarged silent cerebral infarcts). The incidence of the primary end point in the transfusion and observation groups was 2.0 and 4.8 events, respectively, per 100 years at risk, corresponding to an incidence rate ratio of 0.41 (95% confidence interval, 0.12 to 0.99; P=0.04). CONCLUSIONS Regular blood-transfusion therapy significantly reduced the incidence of the recurrence of cerebral infarct in children with sickle cell anemia. (Funded by the National Institute of Neurological Disorders and Stroke and others; Silent Cerebral Infarct Multi-Center Clinical Trial ClinicalTrials.gov number, NCT00072761, and Current Controlled Trials number, ISRCTN52713285.).

Nitric Oxide for Inhalation in the Acute Treatment of Sickle Cell Pain Crisis: A Randomized Controlled Trial

CONTEXT Inhaled nitric oxide has shown evidence of efficacy in mouse models of sickle cell disease (SCD), case series of patients with acute chest syndrome, and 2 small placebo-controlled trials for treatment of vaso-occlusive pain crisis (VOC). OBJECTIVE To determine whether inhaled nitric oxide gas reduces the duration of painful crisis in patients with SCD who present to the emergency department or hospital for care. DESIGN, SETTING, AND PARTICIPANTS Prospective, multicenter, double-blind, randomized, placebo-controlled clinical trial for up to 72 hours of inhaled nitric oxide gas vs inhaled nitrogen placebo in 150 participants presenting with VOC of SCD at 11 centers between October 5, 2004, and December 22, 2008. Intervention Inhaled nitric oxide gas vs inhaled nitrogen placebo. MAIN OUTCOME MEASURES The primary end point was the time to resolution of painful crisis, defined by (1) freedom from parenteral opioid use for 5 hours; (2) pain relief as assessed by visual analog pain scale scores of 6 cm or lower (on 0-10 scale); (3) ability to walk; and (4) patients and familys decision, with physician consensus, that the remaining pain could be managed at home. RESULTS There was no significant change in the primary end point between the nitric oxide and placebo groups, with a median time to resolution of crisis of 73.0 hours (95% confidence interval [CI], 46.0-91.0) and 65.5 hours (95% CI, 48.1-84.0), respectively (P = .87). There were no significant differences in secondary outcome measures, including length of hospitalization, visual analog pain scale scores, cumulative opioid usage, and rate of acute chest syndrome. Inhaled nitric oxide was well tolerated, with no increase in serious adverse events. Increases in venous methemoglobin concentration confirmed adherence and randomization but did not exceed 5% in any study participant. Significant increases in plasma nitrate occurred in the treatment group, but there were no observed increases in plasma or whole blood nitrite. CONCLUSION Among patients with SCD hospitalized with VOC, the use of inhaled nitric oxide compared with placebo did not improve time to crisis resolution. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00094887.

Associated risk factors for silent cerebral infarcts in sickle cell anemia: low baseline hemoglobin, sex, and relative high systolic blood pressure

The most common form of neurologic injury in sickle cell anemia (SCA) is silent cerebral infarction (SCI). In the Silent Cerebral Infarct Multi-Center Clinical Trial, we sought to identify risk factors associated with SCI. In this cross-sectional study, we evaluated the clinical history and baseline laboratory values and performed magnetic resonance imaging of the brain in participants with SCA (HbSS or HbSβ° thalassemia) between the ages of 5 and 15 years with no history of overt stroke or seizures. Neuroradiology and neurology committees adjudicated the presence of SCI. SCIs were diagnosed in 30.8% (251 of 814) participants who completed all evaluations and had valid data on all prespecified demographic and clinical covariates. The mean age of the participants was 9.1 years, with 413 males (50.7%). In a multivariable logistic regression analysis, lower baseline hemoglobin concentration (P < .001), higher baseline systolic blood pressure (P = .018), and male sex (P = .030) were statistically significantly associated with an increased risk of an SCI. Hemoglobin concentration and systolic blood pressure are risk factors for SCI in children with SCA and may be therapeutic targets for decreasing the risk of SCI. This study is registered at www.clinicaltrials.gov as #NCT00072761.

DESIGN OF THE SILENT CEREBRAL INFARCT TRANSFUSION (SIT) TRIAL

Background: Silent cerebral infarct (SCI) is the most common cause of serious neurological disease in sickle cell anemia (SCA), affecting approximately 22% of children. The goal of this trial is to determine whether blood transfusion therapy will reduce further neurological morbidity in children with SCI, and if so, the magnitude of this benefit. Procedure: The Silent Cerebral Infarct Transfusion (SIT) Trial includes 29 clinical sites and 3 subsites, a Clinical Coordinating Center, and a Statistical and Data Coordinating Center, to test the following hypothesis: prophylactic blood transfusion therapy in children with SCI will result in at least an 86% reduction in the rate of subsequent overt strokes or new or progressive cerebral infarcts as defined by magnetic resonance imaging (MRI) of the brain. The intervention is blood transfusion versus observation. Two hundred and four participants (102 in each treatment assignment) will ensure 85% power to detect the effect necessary to recommend transfusion therapy (86% reduction), after accounting for 10% drop out and 19% crossover rates. MRI examination of the brain is done at screening, immediately before randomization and study exit. Each randomly assigned participant receives a cognitive test battery at study entry, 12–18 months later, and study exit and an annual neurological examination. Blood is obtained from all screened participants for a biologic repository containing serum and a renewable source of DNA. Conclusion: The SIT Trial could lead to a change in standard care practices for children affected with SCA and SCI, with a consequent reduction in neurological morbidity.

Erythrocytapheresis limits iron accumulation in chronically transfused sickle cell patients

Cerebrovascular accidents (CVA) as a complication of sickle cell disease occur most frequently in childhood. Life‐long transfusion prevents recurrent stroke, but inevitably leads to iron overload. Although effective chelation exists, many patients are not compliant. Erythrocytapheresis, an automated method of red blood cell exchange, was evaluated as an alternative to control transfusion‐related iron load. Eleven patients with sickle cell anemia and a history of stroke were converted from simple transfusion to pheresis. Total time on pheresis for the group averaged 19 months (range 4–36 months). No significant complications occurred with a mean pre‐pheresis hemoglobin S (Hb S) level of 44%. Blood utilization increased by an average of 50%. The effect of pheresis on serum ferritin depended on the patients pre‐pheresis ferritin level and chelation regimen. Ferritin levels remained stable for chelated patients with ferritin levels ⩾5,000 ng/ml, but decreased in a chelated patient with a pre‐pheresis ferritin level of 4,000 ng/ml. For non‐chelated patients with significant pre‐pheresis iron load, ferritin levels remained stable. No patient on chelation prior to pheresis was able to discontinue deferoxamine. However, one patient with pre‐pheresis ferritin of 500 ng/ml maintained serum ferritin levels <200 ng/ml for 36 months of pheresis without chelation. Pheresis is more expensive than simple transfusion unless the cost of chelation and organ damage from iron overload are considered. Erythrocytapheresis is a safe method of controlling Hb S levels and limiting or preventing iron load in chronically transfused sickle cell patients. Am. J. Hematol. 59:28–35, 1998.

Valproic acid-induced cytopenias: Evidence for a dose-related suppression of hematopoiesis

Valproic acid is an important agent in the management of complex seizure disorders. The drug is being used increasingly in higher doses as a single antieonvulsant agent that produces a good response and has an acceptable level of toxicity. 1 The hematologic side effect primarily reported has been thrombocytopenia, which is believed to be mainly of idiosyncratic or immunologic origin. 2 Neutropenia and erythrocyte aplasia have also been reported, but the cause is unknown. We report a patient with severe erythrocyte aplasia and mild neutropenia associated with valproate monotherapy. The cytopenias were temporally related to escalation of VPA dose. In vitro studies of normal adult bone marrow indicated that VPA levels in the therapeutic range for high-dose valproate monotherapy directly suppressed the growth of hematopoietic progenitors.

The pediatric hydroxyurea phase III clinical trial (BABY HUG): Challenges of study design

Evidence of the laboratory benefits of hydroxyurea and its clinical efficacy in reducing acute vaso‐occlusive events in adults and children with sickle cell anemia has accumulated for more than 15 years. A definitive clinical trial showing that hydroxyurea can also prevent organ damage might support widespread use of the drug at an early age. BABY HUG is a randomized, double‐blind placebo‐controlled trial to test whether treating young children ages 9–17 months at entry with a liquid preparation of hydroxyurea (20 mg/kg/day for 2 years) can decrease organ damage in the kidneys and spleen by at least 50%. Creation of BABY HUG entailed unique challenges and opportunities. Although protection of brain function might be considered a more compelling endpoint, preservation of spleen and renal function has clinical relevance, and significant treatment effects might be discernable within the mandated sample size of 200. Concerns about unanticipated severe toxicity and burdensome testing and monitoring requirements were addressed in part by an internal Feasibility and Safety Pilot Study, the successful completion of which was required prior to enrolling a larger number of children on the protocol. Concerns over recruitment of potentially vulnerable subjects were allayed by inclusion of a research subject advocate, or ombudsman. Finally, maintenance of blinding of research personnel was aided by inclusion of an unblinded primary endpoint person, charged with transmitting endpoint data and monitoring blood work locally for toxicity (ClinicalTrials.gov number, NCT00006400). Pediatr Blood Cancer 2010;54:250–255.

Lipopolysaccharide modulates chemotactic peptide-induced actin polymerization in neutrophils

To study the effect of endotoxin (LPS) on the basal and chemotactic peptide, formyl‐methionyl‐leucyl‐phenylalanine (fMLP) ‐induced alterations in neutrophil cytoskeleton, we purified (>98%) LPS‐free neutrophils (LPS‐ < 10 pg/ml LPS), compared their cytoskeletal organization to that of circulating neutrophils, and examined the effect of LPS exposure on the basal and fMLP‐induced change in the cytoskeleton as reflected by F‐actin content and distribution. Shape, F‐actin content and distribution were monitored by FACS analysis and fluorescence microscopy of NBDphallicidin‐stained cells. The F‐actin content of basal and fMLP‐activated, purified LPS‐ cells is similar to that of circulating neutrophils (defined as cells drawn in LPS‐ buffers at 37°C and analyzed after <10 seconds of ex vivo manipulation). LPS‐ cells are round with a diffuse F‐actin distribution. Exposure of LPS‐ cells to LPS causes cell polarization and F‐actin redistribution without net gain in F‐actin content. Peptide activation of the LPS‐ cell causes actin polymerization, which is preceded by a brief lag time. Exposure of LPS‐ cells to LPS (LPS+) enhances fMLP‐induced actin polymerization by: 1) increasing the maximal extent of polymerization; 2) shortening the lag time preceding polymerization and increasing the rate of polymerization; and 3) lowering fMLP dose required for half maximal F‐actin response. The enhancement depends on LPS dose, duration of exposure, and temperature. To examine the mechanism whereby LPS enhances fMLP‐induced actin polymerization, we determined the predominant end for filament growth in LPS‐ and LPS+ cells, the number of actin nuclei generated in LPS‐ and LPS+ by fMLP activation, and the number and affinity of fMLP receptors on LPS‐ and LPS+ cells by 3[H]fMLP binding. Actin polymerization in both LPS‐ and LPS+ occurs predominantly by monomer addition to the barbed ends of nuclei, and the number of actin nuclei in basal and fMLP‐activated LPS‐ and LPS+ cells is similar. LPS+ cells express three times more fMLP receptors than LPS‐ cells. The results show that LPS‐ cells are similar in cytoskeletal organization to circulating neutrophils, LPS causes shape change without change in F‐actin content, and LPS enhances fMLP‐induced actin polymerization response in neutrophils. The results suggest that LPS enhancement of actin polymerization response is associated with an increase in the number of fMLP receptors expressed on the cell surface.

Effect of hydroxyurea treatment on renal function parameters: Results from the multi-center placebo-controlled BABY HUG clinical trial for infants with sickle cell anemia

Children with sickle cell anemia (SCA) often develop hyposthenuria and renal hyperfiltration at an early age, possibly contributing to the glomerular injury and renal insufficiency commonly seen later in life. The Phase III randomized double‐blinded Clinical Trial of Hydroxyurea in Infants with SCA (BABY HUG) tested the hypothesis that hydroxyurea can prevent kidney dysfunction by reducing hyperfiltration.